In an electric vehicle such as an electric automobile, a hybrid vehicle equipped with an internal combustion engine, and a fuel cell vehicle equipped with a fuel cell or the like, a battery is mounted therein that supplies electrical power to a motor for driving the vehicle, and the battery generates heat by chemical reactions that take place during charging and discharging of the battery.
Suppression or heat generation and temperature rise of the battery is important in order to maintain the operating characteristics of the battery, and to avoid a decrease in the life of the battery.
In FIG. 5 of Japanese Laid-open Patent Publication No. 2013-062023, a battery case cooling mechanism is disclosed. A battery case in which plural series-connected battery cells are accommodated is arranged underneath a vehicle compartment of a vehicle, while a cooling device is arranged in the front of the vehicle, and refrigerant pipes are connected between the battery case and the cooling device.
With the battery case cooling mechanism disclosed in Japanese Laid-Open Patent Publication No. 2013-062023, in a battery case main body, 70% to 80% of the internal volume, which is defined by subtracting a volume occupied by the battery cells from the entire internal volume, is filled with an insulating refrigerant liquid (hereinafter referred to simply as a liquid refrigerant), which is a hydrofluoroether (density≈1500 [kg/m3]), and a remaining 30% to 20% thereof is not filled with the liquid refrigerant to thereby form a refrigerant liquid non-filling space (see paragraph [0015] of Japanese Laid-Open Patent Publication No. 2013-062023).
The liquid refrigerant is vaporized at the time that the battery cells are cooled, and by passing through the refrigerant pipes from the battery case, and being cooled by the cooling device, the refrigerant is liquefied and returned again to the battery case (see paragraph [0025] of Japanese Laid-Open Patent Publication No. 2013-062023).
In FIGS. 1 through 3 of International Publication No. WO 2008/050736, a single laminate type of battery cell in which lithium is used (referred to as a power storage apparatus 5 in International Publication No. WO 2008/050736) is disclosed.
In International Publication No. WO 2008/050736, it is disclosed that the outer surface of a case made of laminated film (it is noted that the case may also be made of a metal material) can be coded by using a cooling medium (see paragraphs [0038], [0049] of International Publication No, WO 2008/050736).
In addition, in International Publication No. WO 2008/050736, it further is disclosed that a cooling mechanism is constituted by housing the battery cells in a sealed container, and filling a coaling liquid in the sealed container, whereby the cooling liquid can be naturally convicted in the sealed container, and a circulating path is connected to the sealed container, and the cooling liquid (a liquid which exchanges heat with the battery cells) can be cooled by a radiator disposed on the circulating path (see paragraph [0050] of International Publication No. WO 2008/050736).